Crankshaft sealing rings????????????

[gordwa]

Im doing a ring job on my 1990 90hp Johnson... I cant really find a lot of info on the crankshaft sealing rings..The manual just says measure the width and I have. They are within the tolerance's specified.I don't understand why you wouldn't measure the depth.They have a kind of sharp feel on the lower edges and if you push them down into where they sit they will sit below the top of the groove they sit in.I have lean miss sometimes and this engine can be a pain to start sometimes.so I want to be sure I don't need new ones before I button it all up....thanks for any thoughts.

 

[Joe Reeves]

Re: Crankshaft sealing rings????????????

Think about it.... if those rings sat down upon the crankshafts surface, they would turn blue within about 3 minutes running time. They seal off by extending above the crankshaft. Just be sure that you stagger the ring gaps... I always installed them 180 degrees apart.

Notice how the piston rings look, extending outside the diameter of the piston as you peer into the cylinder? Same princible.

 

[boobie]

Re: Crankshaft sealing rings????????????

Agree + 1....If the width is in spec you're okay.

 

[btomlins]

Re: Crankshaft sealing rings????????????

Doesn't the OEM manual say to face all the gaps up when installing the crank?

 

[emdsapmgr]

Re: Crankshaft sealing rings????????????

The service manuals don't say anything about the directions of the gaps. They do say to look for chips, visual wear and grooved conditions on the seal rings.

 

[F_R]

Re: Crankshaft sealing rings????????????

Doesn't the OEM manual say to face all the gaps up when installing the crank?

As I understand it, that is so that they will compress easily and not get snagged when installing the crank and crankcase.

Actually, they really don't rotate much in a running engine, the crank spins inside them. However, since they aren't pinned or anything, they can't be expected to stay in their original positions. So, outside of assembly time, position really doesn't matter.

 

[Joe Reeves]

Re: Crankshaft sealing rings????????????

Doesn't the OEM manual say to face all the gaps up when installing the crank?

Perhaps, perhaps not. However, in the field, we sometimes find ways to improve on the manual.

 

[gordwa]

Re: Crankshaft sealing rings????????????

Thanks for the come back everyone...My omc manual does say to have them facing up...

 

[Joe Reeves]

Re: Crankshaft sealing rings????????????

My omc manual does say to have them facing up...

We don't care. Scribble that part out.

 

[boobie]

Re: Crankshaft sealing rings????????????

I always had them facing up but I staggered them.

 

[gordwa]

Re: Crankshaft sealing rings????????????

my omc manual says straight up..my celoc manual says stager..so go figure...I staggered them....

 

[btomlins]

Re: Crankshaft sealing rings????????????

I'm going with experience not some manual. Thanks

 

[boobie]

Re: Crankshaft sealing rings????????????

The reason I used to stager them was, you don't see piston ring end gaps lined up in a straight line, do you ??

 

[Faztbullet]

Re: Crankshaft sealing rings????????????

Did you measure cylinders for out of round and taper??? As posted earlier if seal rings have any defects they need replaced, most of the V-4's I tear down will have at least two seal rings worn resulting in a lip on the edge of it. When reassembling, add a dab of gelseal to the upper/lower bearing retainer surfaces along with center main and engine will be a lot quieter, this is a fitch trick.

 

[F_R]

Re: Crankshaft sealing rings????????????

The reason I used to stager them was, you don't see piston ring end gaps lined up in a straight line, do you ??

Come on boobie, I know that you know what those crankshaft seal rings are for. They aren't like piston rings. There is only one ring between crankcase chambers, not at all related or affected by the other ones in other chambers. But stagger them if you wish. Makes no difference. But your input and expertise is appreciated.

 

[racerone]

Re: Crankshaft sealing rings????????????

These rings must move up and down in the block as the engine changes temperature !------Best to give the edges a wee chamfer with a fine file as I believe edges are too sharp..----They must be lined up as per the manual to reduce chance of breakage on assembly.

 

[boobie]

Re: Crankshaft sealing rings????????????

F_R, What would happen if you broke one or left one out ??

 

[racerone]

Re: Crankshaft sealing rings????????????

Those rings look after crankcase compression.---The engine has 4 seperate crankcase chambers.--A broken ring will cause loss of crankcase compression and a missing ring is even worse.-------Loss of crankcase compression leads to poor scavenging of the cylinder and poor engine performance.

 

[Faztbullet]

Re: Crankshaft sealing rings????????????

What would happen if you broke one or left one out ??

A broke one will affect idle and takeoff but once over da hump it will run on top end but will be a little less responsive. (fought merc warranty over a broken one)